The present invention relates to medical irrigation and aspiration syringes and particularly to urological irrigator-evacuator syringes especially suited for use with a resectoscope in performing a transurethral prostatectomy.
In a medical procedure of this kind, the bladder is prefilled with a sterile solution and the bladder and urethra are evacuated periodically to draw out tissue excised from the prostate. Other tissue present in the bladder such as stones and so forth may also be evacuated. It is desirable to collect evacuated tissue for examination by the surgeon and for laboratory analysis as to the condition of the tissue. An evacuator such as the standard Ellik evacuator is used for irrigating and evacuating the bladder and for collecting tissue. The Ellik evacuator is simple and practical and consists of an hour-glass shaped bowl with a rubber bulb and nozzle fitted to the upper bowl for circulating solution through the urethra and bladder. Tissue entrained in the return flow of solution is to be collected in the lower chamber. It is a limitation of the Ellik evacuator that entrained tissue must settle by gravity in a solution of nearly the same density. There is also the tendency for a portion of the tissue to be carried back into the bladder with recirculation of the solution.
A number of prior art devices have been developed as improvements to the Ellik evacuator with particular attention to the task of efficient separation of tissue from recirculated solution.
U.S. Pat. No. 4,801,292 to Watson discloses a medical pump for debris collection including a bulb or squeeze-type syringe for pumping flushing liquid into the bladder. Bladder efflux returns to the syringe and flows through a basket filter where tissue is trapped for removal and analysis. Efflux continues flowing through the porous filter wall through a first one-way valve and into the squeeze bulb chamber. Recirculation occurs by squeezing the bulb and pressurizing the liquid which now follows a separate path out of the syringe through a second one way valve. The Watson device has an open top end in the basket filter and relies on gravitational force for settling and retention of tissue fragments in the basket. Accordingly, Watson is limited to a vertical orientation of the pump with squeeze bulb lowermost in order to properly collect tissue fragments. Additionally, the gravitational settling of tissue in the sterile solution is time consuming, and any fragments floating in the vicinity of the nozzle are likely to be carried back into the bladder on a subsequent compression of the squeeze bulb.
U.S. Pat. No. 3,892,226 to Rosen discloses a urological irrigation-evacuator including a squeeze bulb for circulating sterile solution for irrigating of the bladder. A specimen collecting receptacle for accumulating tissue washed from the bladder is affixed to the syringe by means of a vertically depending two-way flow conduit. Bladder efflux carrying tissue flows down one conduit path toward the receptacle so that tissue is filtered out of the efflux and collected in the receptacle. The resulting device is cumbersome requiring two-hand operation as well as a considerable volume of solution to fill the two-way conduit and receptacle. The filter consists of a grille in the two-way conduit which is insufficient for effective filtering.
U.S. Pat. No. 4,282,873 to Roth discloses a medical irrigation syringe in which a hollow bulb pump is rotatably mounted to the syringe body so that the irrigating fluid may be pumped directly into and out of a resectoscope or through a circuitous path via a collection receptacle attached to the pump for filtering out tissue. A filter screen is provided along the circuitous path for accumulating tissue which thereafter settles into an open receptacle. Roth requires two-handed operation, and while screening tissue out of the circulation liquid, does not provide means for trapping and segregating tissue from the solution.
U.S. Pat. No. 4,729,764 to Gaultier discloses an irrigator and separator similar in operating principle to the Rosen and Roth patents in providing a circuitous path for sterile fluid carrying tissue evacuated from a body cavity. The evacuated fluid is drawn out and through a filter screen where tissue is retained in a collection chamber. The filtered fluid then returns to the syringe pump chamber. The Gaultier device requires two-hand operation, is cumbersome, and requires a substantial liquid volume to fill the pump and collection chambers.
There remains a need for an evacuator which is simple and practical to use and which efficiently filters and captures tissue entrained in a lavage solution.